1. Field of the Invention
The present invention relates to an exposure-suppressing imaging system, and more particularly to a vehicular imaging system, which is capable of automatically suppressing overexposure regions within a captured image, especially at night, by applying a reflective light modulator in the imaging system.
2. Description of the Related Art
For most imaging systems, image capture at night is usually accompanied with an undesired light exposure within the captured image, as there may be a wide range of brightness variation to a dark environment, for example, a dark tunnel with cars using headlights. In this high-contrast situation, most of the imaging systems, such as camera, may obtain a high-contrast image in which the dark portion is extremely dark and the bright portion is extremely bright, and hence it may cause unclearness in image details.
The foregoing exposure phenomenon is commonly seen on images of driving recorders, which are usually used to capture the road images so as to record the license number for tracking the accident perpetrator. However, at nighttime, most driving recorders has low identification ability to the car license plate number, because the license plates are closed to the taillights where constructs a large brightness difference to the dark environment, and thus render the recorded license plate number unclear on the image.
The reason of the overexposure is primarily related to the CCD light sensor or the CMOS light sensor. Most CCD or CMOS sensors have a lower dynamic range than that of human eyes, meaning that the maximum/minimum light intensity recognition of the CCD or CMOS sensor is not as sensitive as the human eyes.
In view of the foregoing drawback, an imaging system suitable for nighttime use and suitable to be installed in a vehicle is expected.